The present disclosure relates to a power amplifier module. In a mobile communication terminal, such as a cellular phone, a power amplifier for amplifying a radio frequency (RF) signal to be transmitted to a base station is used. As this type of power amplifier, a power amplifier including a common-emitter heterojunction bipolar transistor (HBT) which amplifies an RF signal and an emitter-follower HBT which supplies a bias signal to the base terminal of this common-emitter HBT is known, as disclosed in Japanese Unexamined Patent Application Publication No. 2007-288736.